Front head for rock drills



March 31, 1931. c. c. HANSEN 1,798,257

FRONT HEAD FOR ROCK DRILLS Filed Sept. 23, 1926 IN VEN TOR r e 12881:Egg f I s I,

fi/J" AT ORNEY Patented Mar. 31, 1931 .Frrcr.

PATENT CHARLES'C. HANSEN, OF EAS'ION, PENNSYLVANIA; ASSIGNOR TOINGEBSOLL-RAND COMPANY, OF JERSEY CITY, NEW JERSEY, A GORPOBATION OFNEXV JERSEY FRONT HEAD FOB ROCK D RILLS Application filed September 23,1926.

This invention relates to rock drills and more particularly to fronthead constructions providing renewable wearing members.

In certain types of rock drills and more particularly rock drills fordrilling up-holes, the drill is rotated by hand. In such drills thedrill steel is chucked to the front head to rotate with the drill. Theusual practice has been to provide square shanks on the drill steels andsquare holes in the front heads for the drill steels to fit into. Whenthe front head became worn badly it was the usual practice to replacethe front head. Parts such as the front head must be capable ofwithstanding hard usage and to this end they have usually been made ofcase hardened material. The case hardening is adapted to withstand thewear but as soon as the case becomes worn through the wear is very rapidand the front head must be replaced. Due to the treatment in manufactureand the material of which the front heads are made, these parts areexpensive and contribute considerably to the cost of upkeep of 115 thetool. It is an obiect of this invention to enable front heads of drillsof the type described to be used indefinitely by providing renewablewearing parts.

Other objects and advantages of the inpointed out hereinafter.

In the drawing in which similar reference characters refer to similarparts.

Figure 1 shows a preferred embodiment of 1:5 the invention as applied toa rock drill, the view being taken in longitudinal section and only theforward parts of the rock drill being shown,

Figure 2 is a cross section through the front head taken along the line2-2 of Fig. 1, looking in the direction of the arrows, Figure 3 is across section of a rock drill front head provided with an alternativearrangement and embodiment of the inven- 115 tion Figure 4 is a crosssectional view of the front head of a rock drill provided with a secondalternative arrangement and embodiment of the invention, and

Figure 5 is a cross section of the front Serial No. 137,300.

headof a rock drill showing a third alternative arrangement andembodiment of the invention. 7

Referring to the drawings and more particularly to Figs. 1 and 2, therock drill includes a cylinder A within which a reciprocatory' hammerpiston B is adapted to strike an anvil block C mounted in an anvil blockseat D supported at the front end of the cylinder A. The front head E ofthe rock drill a may be attached in any suitable manner to the anvilblock seat-D, there being an anvil block washer F interposedtherebetween.

The front head E is adapted to grip and transmit rotation to the shankof a drill bearing pressure of the drill steel exists at the cornersand, consequently, the most wear will occur at the surface bearingagainst such corners. In order that the bearlng surfaces may be renewedwhen worn out, such surfaces are provided in this embodiment by longrods H insertable in cylindrical holes K- located .in square formationin the front head E. so vention will be in part obvious and in part Flatsurfaces K extend transversely between. the holes K and lie. in planesextending through the axes of the holes. Rectangular recesses H areformed in the rods H, and the surfaces of the recesses coincide with theflat surfaces K to form a square-hole J similar insize to the section ofthe drill steel.

The holes K may be tapered, ifdesired, to cause the rods H to bind asthey are driven into place. Preferably the rods H are, as

shown, adapted to fit snugly in the bores of driven out in any suitablemanner and re placed.

The upkeep of the tool due to wear on the front head is relatively lowsince the cost of manufacture of the rods H is small as well as the costof inserting them in the front head E. The front head E will lastindefinitely. In the alternative arrangement shown in Fig. 3, the fronthead E is provided with an aperture J having two rods L adapted to bearagainst each corner of the drill steel shank G. To this end the fronthead E is provided with eight bores O entering the aperture J andadapted to receive the rods L. Flat surfaces L are provided on the rodsL to lie flush with the surfaces of the aperture J for forming a squarehole to receive the drill steel shank G. The rods L are simpler toconstruct than the rods H since it is necessary merely to grind the flatsurfaces L 011 one face instead of the notch provided in the rods H. Insome cases it is found that the wear occurs in only one direction of thedrill steel G and in such cases a construction may he provided as shownin Fig. 4, in which the aperture J 2 is broached at each corner as at Pto receive a rectangular rod Q, the flat face Q, of which is adapted tobear against the corner of the drill steel shank G.

Similarly, as shown in Fig. 5, the aperture J may he provided with boresR adjacent each corner of the shank of the drill steel G to receivecylindrical rods S having fiat surfaces S on one side which lie flushwith the surfaces of the aperture J 3 and hear against the corners ofthe drill steel shank G in a manner similar to the rods Q, as shown inFig. 4. It may be simpler to hold the rods S in place in cylindricalbores R than to support the rectangular rods Q, in the broachedapertures P.

I claim:

A front head construction for a rock drill comprising a front headhaving four tapered cylindrical holes arranged in parallelism and insquare formation, said holes opening at the opposite ends of the fronthead, flat surfaces between adjacent holes lying in planes extendingthrough the axes of adjacent holes, cylindrical wearing rods snuglyfitted in the holes, and angular recesses in the rods having surfacescoinciding with the flat surfaces to form a square aperture. thesurfaces of said recesses being held in alignment with the flat surfacesby the frictional engagen'ient of the rods with the walls of the holes.

In testimony whereof I have signed this specification.

CHARLES C. HANSEN.

